This proposal addresses a deficiency of scintillation camera technology, which has direct bearing on cancer imaging in the whole-body using recently developed coincidence detection (CD) methods. These cameras are currently being used as an alternative to the more costly positron imaging tomography (PET) systems for the detection of cancer of the whole body. Although they are gaining wide acceptance, primarily because of their cost and versatility, their sensitivity for tumor detection is much poorer than that of PET. Unquestionably, the performance of CD cameras can be improved by reducing spread of light from gamma ray scintillations produced their crystal detectors. It is suggested in this proposal that light spread can be reduced substantially by modifying the architecture of the crystal. The new designs are expected to make it possible to construct thicker crystals for use in CD cameras, thereby increasing sensitivity by a factor of two. The methods proposed should reduce light spreads in a 30 mm crystal to the same as those exhibited by a 10 mm crystal so as to preserve resolution characteristics for lower energy single- photon imaging applications. This change will also improve the energy and spatial resolutions of CD and, more significantly, increase their count-rate capability (their severest limitation) by several-fold. Ultimately (Phase II and III), this development should lead to the production of scintillation camera plates that will be offered to all camera manufacturers, or as retrofits to existing cameras. There are approximately 3500 camera plates produce a year of which about half are designed for CD imaging. PROPOSED COMMERCIAL APPLICATION This research is expected to make available scintillation crystals for coincident detections (CD) cameras that perform much better than current camera crystals. These camera plates can be sold to all camera manufacturers or retrofitted to existing cameras. The market for CD crystal plates is estimated to be approximately 35 million dollars.